Tommy Morrison’s career reached its pinnacle on a hot June night in Las Vegas, when he stepped into the ring and beat George Foreman to become heavyweight champion.

It reached its nadir when he tested positive for HIV three years later.

The last 20 years of the brash boxer’s life would be defined by extensive legal troubles, erratic behavior and mounting health problems. Morrison would later claim that he never tested positive for the virus that causes AIDs, even as he was hospitalized during the last days of his life.

Morrison died Sunday night at a Nebraska hospital. He was 44.

His longtime promoter and close friend, Tony Holden, confirmed that “the Duke” had died, but his family would not disclose the cause of death. Morrison and his wife, Trisha, continued to deny that the former champion ever had HIV during the final years of his life.

“Tommy’s a very stubborn person and he views things the way he wants to view things. That’s his right and privilege,” Holden said. “All through his career, him and I would come not to physical blows but disagreements on certain things. We always ended up friends. That was Tommy.

“That’s the way Tommy took off after he was told he was HIV-positive,” Holden added. “When he first was told, I was taking him to seek treatment and to different doctors around the country. And then he started research on the Internet and started saying it was a conspiracy. He went in that direction and never looked back.”

The controversy, along with Morrison’s rapid decline, overshadowed a stellar career.

Morrison was a prodigious puncher whose bid to fight in the 1988 Seoul Olympics ended at the hands of Ray Mercer, who later dealt him his first professional loss. Along the way, Morrison became such a recognizable face that he was cast in “Rocky V” alongside Sylvester Stallone.

Morrison won his first 28 professional fights, beating faded champions such as Pinklon Thomas along the way. He hit it big at the Thomas & Mack Center in the summer of 1993 — a unanimous decision over Foreman, then in the midst of his comeback — to claim a vacant world title.

As with so many things in Morrison’s life, the good was quickly followed by the bad.

Morrison was in line for a high-profile bout with Lennox Lewis when he was upset by unheralded fighter Michael Bentt in Tulsa, Okla., not far from where Morrison was raised. He was knocked down three times and the fight was called before the first round ended.

The loss meant a potential $7.5 million payday for a title unification fight simply vanished.

“I zigged when I should have zagged,” Morrison said afterward. “It’s one of those situations you have to live with and learn from it. I’ll be back.”

Morrison indeed came back, but he was never the same feared fighter. He beat a bunch of long shots and faded stars over the next couple of years before getting knocked out by Lewis in the sixth round.

That fight happened in October 1995. By February, Morrison had tested positive for HIV.

He’d been preparing for another fight that winter when his blood test came back positive for the virus that causes AIDs. Morrison’s license was quickly suspended by Nevada, and the ban was, in effect, upheld by every other sanctioning body. Morrison said at a news conference in 1996 that he’d never fight again, blaming his plight on a “permissive, fast and reckless lifestyle.”

His lifestyle never changed, though, even when he stepped away from the ring.

He had already run afoul of the law in 1993, when he pleaded guilty to assaulting a college student. He also dealt with weapons charges and multiple DUI incidents over the years.

Morrison was finally sentenced to two years in prison in 2000, and another year was added to his sentence in 2002 for violating parole.

When he was released, Morrison said his HIV tests were in fact false positives, and he wanted to resume his career. He passed medical tests in Arizona — even as Nevada stood by its decision to suspend his license — and returned to the ring. Morrison fought twice more in his career, winning once in West Virginia and for the final time in Mexico. He finished with a record of 48-3-1 with 42 knockouts.

Morrison started to fade from the public eye in the final years of his life. He tried to stay connected to the sport by opening a gym in Wichita, Kan., but the enterprise was short-lived.

“If Tommy was fighting today, he no doubt would be a world champion,” Holden said. “You have to look at who he was fighting in the ’90s, the guys in that division were Tyson, Lennox Lewis, Riddick Bowe, Ray Mercer, George Foreman. There’s no one with that talent today. Tommy would absolutely dominate if he were in his prime boxing today.”